UNDERSEA TECHNOLOGY 



51 



windows under short term hydrostatic loading at room temperatures. 

 Specimens consisted of 30, 60, 90, 120, and 150 degree included-angle, 

 conical, acrylic windows. 



Approximately 40 specimens were tested for each included angle. Re- 

 sults show a considerable gain in critical pressure for most windows when 

 the included angle is increased from 30 to 60 degrees, but less gain from 

 60 to 90 degrees. Any gain in increasing to 120 and 150 degrees is not 

 significant. For all practical purposes, the 90 degree angle appears to be 

 a significant design factor for windows exposed to near-critical pressure 

 over long periods of time. The factor wUl be examined in long-term 

 window developments. 



The second experimental phase produced design criteria for flat acryHc 

 windows for any ocean depth under conditions of short-term loading. 

 The flat windows under short-term hydrostatic loading were found to be 

 comparable in performance to conical windows with a 90 degree included 

 angle. 



0.1 



0.2 0.3 



0.4 0.5 



t/D 



0.6 0.7 



0.8 0.9 1.0 



Design chart for two types of acrylic windows subjected to short-term hydrostatic 

 pressures. For example, a 90-degree conical window designed for 16,000 psi must 

 have a t/D ratio greater than 0.5, or a thickness of not less than 2 in. with a diameter 

 of 4 in. 



